Thermal insulating structures having a relatively thin outer membrane and an insulating material sealed inside of the membrane are commonly used to insulate household appliances such as refrigerators, freezers, waterheaters, and similar apparatus. Such insulating structures are also utilized in the walls of truck bodies and other vehicles, residential and commercial buildings, and a variety of specialized applications such as around heat producing apparatus, e.g., recessed light fixtures. See U.S. Pat. No. 3,004,877 which issued Oct. 17, 1961 to Simms et al., U.S. Pat. No. 1,942,162 which issued Jan. 2, 1934 to Campbell, and U.S. Pat. No. 4,210,070 which issued July 1, 1980 to Tatum et al. for examples of this type of thermal insulating structure. The outer sheath, or covering, of these insulating structures is typically sealed to the ambient atmosphere to minimize absorption of moisture by the insulating material contained therein and to prevent exchange of cool ambient air with warmer air trapped within the outer sheath. An enhancement of this type of structure is the inclusion of a charge of gas having a low coefficient of thermal conductivity within the sealed membrane instead of air. For an example of this type of structure see U.S. Pat. No. 4,172,915 which issued Oct. 30, 1979 to Shoptak et al. All of the above referenced insulating structures are intended for permanent installation in specific applications. Such insulating structures do not lend themselves to use in applications where the need is seasonal or intermittant and where the insulating structure must be conveniently stored between uses. The primary reason for this is their inherent inability to be adequately compressed for storage without adversely affecting their functional performance subsequent to storage.
The common blanket or comforter used as domestic bedding is of seasonal use and is typically folded for convenient storage. However, such blankets or comforters are substantially inferior in overall thermal insulating qualities to the thermal structures used in permanent installations described above and therefore would not be suitable for insulating accessways, door openings, and the like.
What is needed is a thermal structure having a high degree of thermal insulating ability combined with the ability to be compressed into a relatively small package for convenient storage and subsequently reused without any substantial loss of utility.